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H. D.- DUNBAR & W. L. AUSTIN. STEAM BRAKE MECHANISM FOR LOCOMOTIVES.

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H. DUNBAR 81; 'W. L. AUS T STEA AKE MECHANISM FOR LOGOM ES.- Patented Dec. 23, 1890.

U TED STATES PATENT Prion.

HENRY D. DUNBAR, or NORTH HARTLAND, VERMONT, AND WILLIAM L. AUSTIN, or PHILADELPHIA, PENNSYLVANIA.

STEAM-BRAKE MECHANISM FOR LOCOMOTIVES.

SPECIFICATION forming part of Letters Patent No. 443,272, dated December 23, 1890.

Application filed April 10, 1890.

To all whom it may concern.-

Be it known that we, HENRY D. DUNBAR, a citizen of the United States, and aresident of North Hartland, Vindsor county, Vermont, and WILLIAM L. AUSTIN, a citizen of. the United States, and a resident of Philadelphia. Pennsylvania,have invented certain Improvements in Steam-Brake Mechanism for Locomotives, of which the following is a specification.

Our invention consists of certain improve ments in or modifications of the steam-brake valve mechanism for locomotives shown in our patent, No. 9,508, dated January 14, 1890, the objects of our present improvement-s being to simplify the construction of the valve and to provide for the circulation of steam through the brake-cylinders and prevent any accumulation of water of condensation in said cylinders. These objects we attain in the manner hereinafter set forth, reference being had to the accompanying drawings, in which-- Figure l is a diagram showing the brakecylinders of a locomotive with our improved valve and pipe connections. Fig. 2 is aplan view of the valve-seat. Fig. 3 is a transverse section of the complete valve on the line 1 2, Fig. 2. Fig. at is an inverted plan view of the valve. Figs. 5, 6, 7, and 8 are diagrams illustrating the different conditions of working, and Figs. 9 and 10 are diagrams illustrating modifications of parts of the invention.

In Fig. 1, A A represent the opposite driver-brake cylinders of a locomotive, and B represents a central cylinder, which is sometimes employed for operating the brakes on the tender.

\Vith the lower end of the cylinder A com municates a steam-inlet pipe D, and from the lower end of the cylinder A to the lower end of the cylinder A extends a pipe-E, which communicates with the lower portion of the cylinder B through a valved branch E.

From the lower portion of the cylinder A extends a disoharge-pipe F, and both pipes D and F are carried up to the casing of the brake-valve G, which is suitably located in the cab of the engine, so as to be within convenient reach of the engineer.

Modifications in the arrangement of the Serial No. 347,303. (No model.)

pipes are possible, however, within the scope of our invention, one such modification being that represented in Fig. 9, in which the pipe E communicates through branches with the bottoms of the cylinders A A and with opposites sides of the cylinder B.

' The pipe D for supplying steam to the brake-cylinders communicates with an induction-port d in the bottom of the valve-casing, and the discharge-pipe F communicates with an eduction-port f therein, the casing having also a centrally-located steam-supply port 1' and an exhaust-port m, the supply-port communicating with the steam-pipe I and the eX- haust-port with an exhaustpipe M, as shown in Fig. 2.

At one side of the induction-port (Z of the valve-seat is a tapering notch cc, and the eduction-port f of the valve-seat has a like tapering notch :r.

The valve N is in the form of a segment, having in its under side a segmental pocket or chamber at, for a purpose described hereinafter, and said valve is operated by aspindie P, passing through a stuffing-box on the cap or cover of the valve-casing.

The operation of the device Will be understood on reference to Figs. 5, 6, 7, and 8. hen the valve is in the position shown in Fig. 5, the induction-port d is covered by the valve and steam from the supply-port i can gain no access thereto, the eduction-port fbeing in communication with the exhaust-port m through the pocket or chamber at of the valve. If it is desired to permita circulation of live steam through the cylinders, so as to keep the latter hot and prevent an accumulation of water therein due to condensation, the valve N is turnedin the direction of the arrow, Fig. 5, to the position shown in Fig. 6, so as to uncover or partially uncover the notch 50 of the induction-port d, and thus permit steam to enter said port and pass through the pipe D to and through the cylinder A, through the connecting-pipe E into the cylinder B, to and through the cylinder A, and thence through the pipe F to the eduction-port f and through the chamber a of the valve to the exhaust-port, this circulation of live steam serving to keep the cylinders hot and prevent the accumulation of water of condensation therein, any such water of condensation being blown from the cylinders A A and draining from the cylinder 13 into the pipe E, from which it is likewise blown by the ilow of steam through said pipe. If it is desired to apply the brakes with less than the full power, the valve N' is turned a little farther in the direction of the arrow, Fig. ti, or to the position shown in fliig. 7, so as to open and increase the area of the port (I for the entrance of the steam and contract; the area of the eduction-portf. ll'ence steam can enter the cylinders more rapidly than it can escape therefrom, thus imparting a certain degree of pressure to the pistons in said cylinders. It the brakes are to be applied with full force, the valve is turned in the direction of the arrow, Fig. '7, to the position shown in Fig. 8, so as to fully open the induction-port (Z and close the educt'ion-port f.

The valve which we have thus shown and described is somewhat simpler in construction than the valve shown in our former patent, and the connections between the valveehest and the brake-cylinders provide for an etfective circulation of steam from the valveehest through the cylinders and back to the valve-chest again.

If desired, the tapered notches :1: as may be formed in the valve instead of in the valveseat, as shown in Fig. 10.

In case of any-detect in the brake operated by the cylinder 1 said cylinder can be cut off from the pipe E by closing the valve in the branch 1 1,or the valve may be closed when the cylinder 13 is not required to be used, and it will be evident that our system of eirculating-pipes can be used in connection with locomotives which are not provided with this central cylinder 13.

The connections of the pipes D, E, and 1 with the cylinders A A provide for the application of the brakes by an upward movement of the pistons in said cylinders. When the brakes are to be applied by a downward movement of the pistons, the pipes will coininnnicate with the upper ends of the cylinders. I

Independent valves on the supply-pipe l) and discharge-pipe 1 might also be used in some cases for controlling the flow through the same; but as multiplicity of valves is always to be avoided in a locomotive-engine the single valve, as shown, is preferred in all cases.

Our invention may also be adopted in connection with engines having but a single cylinder for operating the driver-ln'akes, instead of independent cylinders for each brake, as shown.

' llaving thus described our invention, we claim and desire to secure by Letters Patent 1. The combination of the driver-brake cylinder or cylinders of a locomotive with a stez'un-supply pipe leading to said cylinder or cylinders, an independei'it discharge-pipe leading from the same, and a valve or Valves whereby the flow of steam into the inlet-pipe and the escape of steam from the outlet-pipe may be regulated, substantially as specified.

2. The combination of the driver-brake cylinders of a locomotive with a pipe for supplying steam to the end of one cylinder, a pipe discharging steam from the end of the other cylinder, a pipe connecting said ends of the cylinders, avalved steam-induction port communicating with said cylinder supplypipe, and a valved eduction-port communicating with the cylinder discharge-pipe, whereby a circulation of steam to and through the cylinders in succession and thence to the exhaust is permitted, substantially as specified.

The combination of the driver-brake cylinders of a locomotive, a tender-brake cylinder, a pipe for supplying steam to one end of one driver-brake cylinder, a pipe for discharging steam from one end of the other driverbrake cylinder, a pipe connecting said cylinders and having a branch communicating with the tender-brake cylinder, a valved induction-port communicating with the cylin' der supply-pipe, and a valved cduction-port communicating with the cylinder dischargepipe, substantially as specified.

l. The combination of the valve-chest having induction, eduction, supply, and exhaust ports, the valve having a supply-passage and discharge chamber or pocket in its under side, and tapering extensions of the induction and eduction passages of the valve or chest, substantially as specified.

I11 testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

HENRY D. DUN BAR. WM. L. AUSTIN. \Vitnesscs:

WILLIAM I. WALL, J. R. Mnssnv.

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